Summary of studies, which demonstrated relationships between levels of MDSCs and tumorigenesis in CRC patients
| Sample type | MDSC phenotype | Number of samples | Main findings | References |
|---|---|---|---|---|
| Peripheral blood | Lin–/lowHLA-DR– CD11b+CD33+ MDSCs | 64 patients | Increased percentage and the absolute number of Lin–/lowHLA-DR–CD11b+CD33+ MDSCs compared with healthy controls. This increase is closely correlated with clinical cancer stage and tumor metastasis but not primary tumor size | [20] |
| Peripheral blood | CD11b+CD33+HLA-DR– MDSCs | 23 patients with stage IV metastatic CRC | Patients with advanced CRC display enhanced MDSC levels and reduced CD247 expression | [37] |
| Peripheral blood and tumor tissues | CD33+HLA-DR– MDSC | 49 CRC patients | A considerable increase in the percentage of CD33+HLA-DR– MDSCs was observed in the peripheral blood and tumor tissues of CRC patients as compared with healthy controls | [18] |
| Peripheral blood and tumor tissues | CD33+CD11b+HLA-DR– | 32 age-matched healthy donors and 42 patients with CRC at the time of first diagnosis | CRC patients had elevated levels of CD33+CD11b+HLA-DR– MDSCs in primary tumor tissues and in peripheral blood. These elevated circulating MDSCs were correlated with advanced TNM stages and lymph node metastases | [42] |
| Tumor tissues | CD45+Lin–HLA-DR– CD11b+CD33+CD66b+ | 154 patients with colorectal adenocarcinoma | Activated inflammatory-DCs induced γδT17 cells to secrete IL-8, tumor necrosis factor alpha, and GM-CSF with a concomitant accumulation of immunosuppressive PMN-MDSCs in the tumor | [44] |
| Tumor tissues | CD33+CD11b+HLA-DR– MDSCs | 145 newly diagnosed CRC patients who did not accept any preoperative chemoradiotherapy | A significant association between CD33+ MDSC number and YAP1 and PTEN levels in CRC patients. The CD33+ MDSCs, YAP1, and PTEN were identified as predictors for the prognosis of CRC patients | [46] |
| Peripheral blood and tumor tissues | CD33+CD11b+HLA-DR–/lowCD15+CD33+CD11b+HLA- DR–CD14–CD15− | 21 CRC and 21 healthy donors | The expansion of peripheral GMCs correlated with higher stage and histological grade of cancer, thereby suggesting their role in cancer progression | [47] |
| Peripheral blood | M-MDSCs were detected as CD45+CD11b+CD33+HLA- DRlowCD14+CD15–, G-MDSCs (CD33hi PMN- MDSC) were detected as CD45+CD11b+CD33hiHLA- DRlowCD14–CD15+ | 10 patients with advanced colorectal carcinoma | Levels of circulating M-MDSCs were not associated with metastatic disease within advanced CRC patients. Levels of circulating CD33hi PMN-MDSCs were elevated in patients with distant metastases compared to T3 M0 subgroup | [52] |
| PBMC | M-MDSCs (defined as CD14+HLA-DR–/low) PMN-MDSCs (defined as low density, CD33+CD11b+CD14– CD15+SSChi) | 1 CRC patient and 8 healthy donors | A significant expansion of CD38+ M-MDSCs and a trend of expansion of CD38+ PMN-MDSCs (accompanied by a trend of increased CD38 expression on both M-MDSCs and PMN-MDSCs) were observed in PBMCs of CRC patients when compared with healthy donors | [54] |
PBMC: peripheral blood mononuclear cell
